Harmonic nozzle drive

ABSTRACT

Surface cleaning equipment comprising a housing containing a fluid driven impeller and a closed chamber through one end of which passes an impeller-driven shaft and through the opposite end of which passes an output shaft which drives an orbital spray nozzle receiving the impeller exhaust fluid from a housing passage outside the chamber, the output shaft being driven at reduced speed by transmission of the impeller shaft rotation through a wave generator-harmonic drive gear mechanism contained in the chamber.

United States Patent [191 Keller et al. Sept. 2, 1975 HARMONIC NOZZLEDRIVE 3,326,468 6/1967 Bristow et al 239 240 3,416,732 12 196 R 239 227[75] Inventors: Robert F. Koller, Philadelphia; Jay 8 ener W. Lord, Jr.,Wayne, both of Pa. V Primary Exammerl ,loyd L. King Asslgneer PurexCorporation Lld-, Lakewood, Attorney, Agent, or Firm-White and HaefligerCalif. V

[22] Filed: Sept. 20, 1974 57 A TR [21] App]. No.1 507,809 Surfacecleaning equipment comprising a housing containing a fluid drivenimpeller and a closed chamber 52 US. Cl 239/227; 239/240 through one endwhich Passes imPener'driven 51 Int. 01. B05B 3/00; BOSB 3/04 shaft i fit; f 2? i whlch 58 Field of Search 239/227, 240 F s a w Spray e ceivmgthe impeller exhaust fluid from a housing pas- [56] References cued sageoutside the chamber, the output shaft being driven at reduced speed bytransmission of the impel- UNITED STATES PATENTS ler shaft rotationthrough a wave generator-harmonic 2,714,080 7/1955 Kennedy, Jr. et a1239/227 drive gear mechanism contained in the chamber 2,9l7,243 12/1959Lione 239/227 3,275,241 9/1966 Saad 239/240 11 Claims, 6 Drawing Figures1 18 I2 I8 7 I7- 50 iLfig i w -2e -7 I a Z223 21 7 $42 72- 4-73 74 w W63 39 7x15 24 l 2 a \4 a7 3/ 57 I4 m 82a 99 45 HARMONIC NOZZLE DRIVEBACKGROUND OF THE INVENTION The general kind of cleaning equipment withwhich the invention is concerned and as typified in US. Pat. No.3,416,732, issued Dec. 17, 1968. entitled WASHING APPARATUS FOR ENCLOSEDSPACES, employs the general combination of a housing containing a fluiddriven impeller the output shaft of which drives one or more nozzles inan orbital path about the housing axis and which receive the impellerwater or cleaning solution effluent.

Harmonic drive mechanisms which are the subject of US. Pat. No.2,906,163 issued Sept..29, 1959 to C. W. Musser on Strain Wave Gearing,are known to utilize a traveling wave generated in a flexible endlesscomponent and the motion conversion that results from an advancing waveshape.

A non-rigid mechanical element is used for the generation of acontinuous deflection wave capable of achieving a very high mechanicalleverage and of transmitting rotary and linear forces through steelwalls. Theory conversion to practical usefulness in harmonic drives isaccomplished by using three basic elements; a circular spline, aflexspline and a wave generator. While these elements may take alternateforms in units designed for special application, the type herein shownis representative of the form useable for the present invention.

In the basic harmonic drive configuration, the wave generator is theinput element. It imparts an ellipse-like shape to the non-rigidflexspline that normally functions as the output element. The circularspline is a rigid circular fixed member with internal teeth that areprogressively meshed with those of the flexspline by the wave generator.

The difference in relative rotary motion is due to the difference in thenumber of teeth between the flexspline and the circular spline. Thereduction ratio, R, of a harmonic drive transmission is determined bythe formula:

wherein N is the number of teeth in the flexspline and N is the numberof teeth in the circular spline. Teeth on the flexspline and circularsplines are cut to the same circular pitch with the smaller internalflexspline carrying slightly fewer teeth than the circular spline. Thiswill make the above ratio, R, have a negative value which means that theflexspline and wave generator turn in opposite directions.

Advantages of the harmonic drive are high speed reduction in a singlestage along with high torque capacity relative to the size and weight ofa unit. Spline teeth come into contact almost by pure radial motion andhave essentially zero sliding velocity, making friction and wear lossesalmost negligible. Advantages from this feature make high mechanicalefficiencies at high rathan one set of spline teeth are in simultaneousengagement resulting in high torque capacity. Teethadjacent to loadbearing teeth are in near engagement which provides resistance to shockoverloads. Regions of tooth engagement and application of load torqueare diametrically opposed, resulting in a force couple that issymmetrical'and balanced. Concentricity of the elements tendto make theharmonic drive self-aligning.

SUMMARY OF THE INVENTION The invention has for its general object toemploy the harmonic drive principle in a new environment and manner-as aspeed reducing transmission between an impeller driven shaft and anoutput shaft which drives one or more washing or spray nozzles, thus toimprove the control, stability and efficiency of the washing operation.

More particularly the invention contemplates cleaning equipmentcomprising a housing having a fluid inlet and containing a fluid drivenimpeller from which the fluid flows through a passage in the housing,harmonic speed reducing mechanism interposed in effect between theimpeller shaft and a nozzle drive shaft receiving the impeller effluentfrom the housing fluid passage.

In its preferred form the invention provides within the housing a closedchamber spaced therefrom to define the fluid passage and receivingthrough one end the impeller shaft which drives a wave generatoroperating within a flexible gear or flexspline having teeth contactingthe differentially numbered teeth of a rigid gear mounted to the chamberwall, the flexspline being connected through the bottom of the chamberwith the reduced speed nozzle shaft.

Particularly adaptable to efficient structure and operation of theinvention is the use of a harmonic drivetransmission .in-which theflexspline has the form of a radially flexible cup, the open end ofwhich receives the wave generator inside the flexible gear and theopposite or closed end of the cup being connected to the nozzle rotatingshaft. 1 i

These and additional features, objects and details of the invention willbe more fully understood from the following detailed description of anillustrative embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the cleaningapparatus in vertical medial cross section; a

FIG. 2 is a section looking upward as viewed from line 22 of FIG. 1;

FIG. .3 is a view in the same plane looking downwardly; i v

FIG. 4 is an enlarged cross section on line 44 of FIG. 1; I

FIG. 5 is a fragmentary vertical section taken on line 5-5 of FIG. 4;and

FIG, 6 is an exploded perspective showingthe harmonic drive parts.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT Assuming the apparatus to bevertically oriented as in FIG. 1, the assembly is shown to comprise ahousing 10 the tubular body 11 of which is connected by head 12 and pipeor hose coupling 13 to pressurized water orcleaning-solution source.Bottom 14 of the body mounts the spray nozzles as will appear. Inletdisc 15 secured tov head 12 by screws 16 contains angular openings 17(see FIG. 2) registering with inlet holes 18.and which direct the liquidagainst vanes 19 carried by the impeller 20 to produce its rotation. I

The housing contains an axiallyalinedclosed chamber, generally indicatedat 21, which may be rendered water tight by appropriate use of seals.The chamber is defined by its wall 22 which is annularly spaced at 23from the housing shell 1 1 to form a passage for the impeller efflu'entgoing to the nozzles as will appear. The chamber 21 has a top closure 25secured to the wall 22 byscrews 26 and contains a central'opening 27through which passes the impeller shaft 28 within seal ring 29 v andbearing 30. I I

The impeller drive is transmitted to the orbiting nozzle 31 by way ofreduced speed flexspline adaptor shaft 32b connected to output shaft 32by screw 24 and extending through the lower ends of both housing 10 andchamber 21 within bearings 33 and 34 and seal rings 35, 36. Lowertubular extent 32a communicates through its openings 37 with annularspace 38 which connects with passage 23 through one or more openings 39.The bottom shaft extent 32a is threaded at 40 within T fitting 41 intowhich is threaded tubular laterals 42 which mount bevel gears 43 forrotation on bearings 44 in planetary relation with gears 45 secured tothe housingpart 14 by screws 46. The laterals 42 also mount the nozzlebodies 47 which arefixed to gears 43 for rotation on bearings 48, 49.Thus the liquid is delivered through the shaft and lateral passages 50and 51 to the nozzles traveling an orbital path about the housing axis.Handle 52 may be provided for manipulation of the unit.

- Turning now to the harmonic drive transmission generally indicated at54 and as particularly shown in F1GS."4, 5 and 6, its components includea collar coupling 55 having flange 56 and drilled hole at 57 to receivepin 58 to key the coupling against rotation on the impellershaft 28.Externally the coupling may have a snap ring groove 59 and internallythe coupling has diametrically slotted ways 60 for reception of key lugs61 projectinginward from locking ring 62 and diametrically opposed keylugs 61a at right angles to key lugs 61 on lock ring 62 extendingthrough key ways 63 in the wave generator 64. The described assembly isheld in its FIG. 5 relation by retaining ring 65 and snap ring 66. Wavegenerator 64 is thus interlocked with the impeller shaft for rotationtherewith at its speed.

The wave generator rotates within a force transmitting bearing assemblygenerally indicated at 67 and comprising radially flexible raceways 68and 69 for the bearings 70. Raceway 69 is adhered to the inside openflexible mouth of cup shaped flexspline 71 to the bottom of which isconnected the flexspline adaptor shaft 32b by screws 72 passing throughclamp ring 73. Flexspline adaptor shaft 32b is connected to the outputor driver shaft 32 by screw 24. Needle bearings 74 may be provided tojournal the impeller shaft terminal radially.

Adhered to the outside of the flexspline mouth is a radially flexiblegear 75 the teeth 76 of which are contactable with the teeth 77 ofcircular rigid gear 78 held to the chamber 21 wall 22 by screws 26.Bearing retaining ring-79 is connected by screws 80 to the wavegenerator for rotation therewith in overlying relation to the bearingassembly 67. As particularly shown in FIG. 4 the wave generator 64 byreason of its elliptical shape operates to deflect the flexible bearing67, i.e., its race rings 68 and 69, the wall of flexspline 75 and itsteeth 76 in an elliptical progression or wave so that the flexible andrigid gear teeth 76 and 77 are caused to interengage from their opposedclearances at 81 along their opposed engaged courses at 82. Gear 78being held stationary the flexspline gear becomes rotated by virtue ofthe fewer number of gear teeth than gear 78 and in a direction oppositethe rotational direction of the impeller shaft 28.

Typically the rigid and flexible gears may be cut to pitch diameter ofabout 2.06 inches with rigid gear having 162 to 322 number of teeth andthe flexible gear carrying to 320 teeth. In this ratio the output shaft32 will be driven in a reduced speed within the range of about 50 to 200to 1 rpm of the impeller shaft which may be assumed to rotate from50-2000 rpm depending on the quantity of fluid passing through impeller20. Thus the speed ratio may be in the range of about 0.5 to 2% of theimpeller rotary speed. Chamber 21 may contain a suitable lubricant forthe gears and other rotating parts contained therein.

1 claim:

1. Drive for an orbital nozzle comprising a housing having a fluid inletand containing a fluid driven impeller from which the fluid flowsthrough a passage within the housing, harmonic rotary speed reducingmechanism in the housing comprising an inner relatively flexiblerotating gear having teeth meshing with the differentially numberedteeth of an outer relatively rigid gear, a rotating wave generatordriven by said impeller and operable to flex said,inner gear in wavesequence, an output shaft driven by said inner gear at speed reducedbelow the impeller speed, and means driven by said output shaft mountingsaid nozzle for rotation including means for delivering fluid from saidpassage to the nozzle.

2. Drive according to claim 1 in which said driven shaft is rotated at aspeed within the range of about 0.5 to 2% of the impeller rotary speed.

3. Drive according to claim 1 in which said inner gear is joined to theopen top of a gear splined cup axially centered in the housing and tothe bottom of which said shaft is connected.

4. Drive according to claim 1 in which said gears are contained in achamber through one end of which passes a shaft driven by the impellerand through the opposite end of which said driven shaft extends.

5. Drive according to claim 3 in which said gears are contained in achamber through one end of which passes a shaft driven by the impellerand through the opposite end of which said driven shaft extends.

6. Drive according to claim 4 in which said chamber is water tight andcontains a gear lubricant.

7. Drive according to claim 4 in which said chamber is contained withinthe housing and said passage is between the chamber and housing.

8. Drive according to claim 7 in which said inner gear is joined to thetop of a radially flexible cup depending within the chamber and to thebottom of which said output shaft is connected.

9. Drive according to claim 8 in which said wave generator rotateswithin and flexes said cup and flexible gear in an elliptical course.

10. Drive according to claim 9 in which the impeller driven shaftextends through the bottom of said cup.

1 1. Drive according to claim 10 in which the impeller shaft isjournaled for rotation within said output shaft.

1. Drive for an orbital nozzle comprising a housing having a fluid inletand containing a fluid driven impeller from which the fluid flowsthrough a passage within the housing, harmonic rotary speed reducingmechanism in the housing comprising an inner relatively flexiblerotating gear having teeth meshing with the differentially numberedteeth of an outer relatively rigid gear, a rotating wave generatordriven by said impeller and operable to flex said inner gear in wavesequence, an output shaft driven by said inner gear at speed reducedbelow the impeller speed, and means driven by said output shaft mountingsaid nozzle for rotation including means for delivering fluid from saidpassage to the nozzle.
 2. Drive according to claim 1 in which saiddriven shaft is rotated at a speed within the range of about 0.5 to 2%of the impeller rotary speed.
 3. Drive according to claim 1 in whichsaid inner gear is joined to the open top of a gear splined cup axiallycentered in the housing and to the bottom of which said shaft isconnected.
 4. Drive according to claim 1 in which said gears arecontained in a chamber through one end of which passes a shaft driven bythe impeller and through the opposite end of which said driven shaftextends.
 5. Drive according to claim 3 in which said gears are containedin a chamber through one end of which passes a shaft driven by theimpeller and through the opposite end of which said driven shaftextends.
 6. Drive according to claim 4 in which said chamber is watertight and contains a gear lubricant.
 7. Drive according to claim 4 inwhich said chamber is contained within the housing and said passage isbetween the chamber and housing.
 8. Drive according to claim 7 in whichsaid inner gear is joined to the top of a radially flexible cupdepending within the chamber and to the bottom of which said outputshaft is connected.
 9. Drive according to claim 8 in which said wavegenerator rotates within and flexes said cup and flexible gear in anelliptical course.
 10. Drive according to claim 9 in which the impellerdriven shaft extends through the bottom of said cup.
 11. Drive accordingto claim 10 in which the impeller shaft is journaled for rotation withinsaid output shaft.